基于非本征/本征缺陷构建陷阱储能型可再生应力发光材料

Recoverable mechanoluminescent (ML) materials are an emerging class of trap-controlled energy-storage phosphors that repeatedly respond to nondestructive mechanical stimuli and produce light emissions, showing tremendous potential applications in the visualization of stress distribution, structural health monitoring, life sciences, displays and lightings. Trap centers, luminescent centers and piezoelectricity are the essential features of most recoverable ML materials. Accordingly, the traditional method to search for recoverable ML materials is primarily based on screening of existing persistent phosphors displaying piezoelectricity. Given the limited number of available candidate persistent phosphors, the family of recoverable ML materials known to date is relatively small, of which an extremely small portion shows high ML performance. The shortage of material systems has become a major obstacle to the understanding and application of recoverable ML. This project thus employs the piezoelectric hosts with a larger number than persistent phosphors, and proposes two strategies to create luminescent centers and trap centers. One is a doping method to introduce luminescent ions and extrinsic defects by doping activators. Another is an un-doping method to form intrinsic defects which serve as combination levels and trap levels. The main content is to investigate the effective paths to create and manipulate the luminescent centers and trap centers, as well as the deformation characteristics of piezoelectric crystal structure. Through the systematical and in-depth study on the properties of luminescent centers, trap centers and piezoelectricity, it is devoted to reveal the coupling rules among those essential features, to explore and summarize the design principles of high-performance (high-brightness, hypersensitive and wide-range-stress sensing) recoverable ML materials. These studies are expected to establish new design strategies and largely expand the horizons of existing recoverable ML materials, thereby paving the way for the fundamental research and promising applications of recoverable ML.

可再生应力发光材料在非破坏机械载荷下可将陷阱储存的能量以光发射形式循环释放，近年来在可视化应力探测、结构健康监测、生命科学、照明与显示领域展现出良好的发展前景。陷阱中心、发光中心和压电性是绝大多数可再生应力发光材料的基本要素，在长余辉材料中筛选压电性是开发该类材料的传统方法。但受制于长余辉材料有限的供体数量，可再生应力发光材料开发缓慢且高性能材料匮乏，极大限制了其实用进程。本项目以供体更广的压电材料为基质，提出“非本征缺陷法—激活剂掺杂创造发光中心和陷阱中心”和“本征缺陷法—基于本征缺陷俘获和复合受激载流子”两种材料设计策略，重点研究发光中心和陷阱中心的有效创造和调控途径及基质晶格形变行为，揭示构建“压电场-陷阱中心-发光中心”关联耦合的物理机制，探索和归纳高性能（高亮度、高敏感、宽应力响应）可再生应力发光材料的开发原则；在发展新设计方法的同时，丰富材料种类，推动该类材料的研究及应用。

可再生应力发光材料具有结构无损、发光可再生的机-光转化特性，在应力分布可视化探测、结构健康诊断、力驱动的照明与显示、光学信息存储等领域具有广阔的应用前景。对应力发光机制认知不足和材料供体匮乏是当前阻碍可再生应力发光应用进程的主要瓶颈。针对上述问题，本项目沿着可再生应力发光的构建开发-机理解析-多模式耦合的主线，开展了三方面的研究工作。. 1. 在可再生应力发光的构建策略和材料开发方面，归纳了绝大多数可再生应力发光材料（少数属于摩擦电类材料）的本质特征是压电场-载流子陷阱-发光中心的有效耦合，提出了压电基-非本征/本征缺陷法的材料构建策略，设计开发了十种新型可再生应力发光材料，为该类材料的有效、快速开发明确了大方向，也为深入探究应力发光机制奠定了材料基础。. 2. 在应力发光机理解析方面，通过构建晶体/电子微结构演化平台，揭示了能带结构-陷阱态-电子能级关联系统影响和调控应力发光的若干微观机制，包括应力发光的电子隧穿效应、陷阱辅助的能量传递过程、局域压电性驱动应力发光等机制，为高性能应力发光材料的按需设计提供了较为系统性的实验和理论基础。. 3. 在应力发光与多重光学模式耦合方面，提出了“压电基双镧系发光多路复用”和“压电刺激差异化激励色心和余辉陷阱”策略，创新性地在单一材料中实现了四模式（应力发光、热释光、上转换/下转移发光）、双寿命（延时和瞬时荧光）、多色发光功能的耦合，以及压电响应的明场（光致变色）和暗场（长余辉）信息差异化显示，为面向不同应用目标的高性能应力发光材料的设计开发提供了新思路。. 相关研究成果以第一作者/通讯作者发表SCI论文12篇，包括Progress in Materials Science、Advanced Materials、Advanced Functional Materials（2篇）、Acta Materialia、Chemical Engineering Journal、Applied Physics Letters等。受邀撰写中文综述2篇。以第一发明人授权美国、中国发明专利各1项，申请中国发明专利1项。受邀国际/国内学术会议邀请报告6次。培养硕士研究生8名。